Academic journal article Bulletin of the World Health Organization

The Future of the HIV Pandemic

Academic journal article Bulletin of the World Health Organization

The Future of the HIV Pandemic

Article excerpt

The "next wave"?

Recent predictions of a catastrophic "next wave" of the HIV pandemic in the populous countries of Asia and Eastern Europe (1, 2) are a cause of controversy within international development agencies and have been condemned by some of the national governments concerned (3). The predictions suggest that prevalent HIV infections in China, India and the Russian Federation alone could reach between 35 million and 68 million in 2010, compared with the current global total of 38 million estimated by the Joint United Nations Programme on HIV/AIDS (UNAIDS) and WHO (4). Undoubtedly the drugusing and sexual behaviours that transmit HIV are increasing in these countries (5), and numbers of newly diagnosed HIV infections have surged in recent years (4). However, next-wave scenarios are contingent on a generalized heterosexual spread occurring on a scale similar to that seen in sub-Saharan Africa. Is this possible?

While many studies have shown the correlation between an individual's sexual behaviour and infection with HIV, there is little evidence for population-level measures that can explain differences in adult HIV prevalence (6-8). This lies at the heart of the difficulty in forecasting the scale of heterosexual HIV epidemics, because no measures of sexual behaviour in the population have been identified as accurate predictors of the size of an epidemic. Current forecasts therefore have to rely on scenarios proposed by experts using Delphi or similar techniques or on mathematical models. Models that attempt to forecast the size of a heterosexual HIV epidemic tend to be based either on fitting epidemic curves to available prevalence data and extrapolating (9) or on mathematical descriptions of sexual behaviour and the associated transmission of HIV (IO). There is a massive level of uncertainty in such forecasts (5). Thus, while next-wave scenarios can be deemed unlikely or derived through applying a worst-case scenario systematically (11), they can only ever be disproved after the event. It is the role of UNAIDS, WHO and the scientific community to make clear what can and cannot be said about the future of the HIV pandemic. If accurate forecasts are so problematic, is there an alternative approach that can be adopted?

Distinct epidemics

In most countries of Asia and Eastern Europe, in contrast to sub-Saharan Africa, HIV currently remains concentrated within identifiable vulnerable populations such as injecting drug users and their sex partners, men who have sex with men, and sex workers and their clients. In many of these countries it has been possible to estimate the size of these populations, using data from surveys and censuses or indirect estimates based on multiplier or capture-recapture techniques (12). HIV prevalence estimates from sentinel surveillance sites among these populations can then be multiplied by population size to estimate the number of people infected with HIV. UNAIDS and WHO have developed software and held training workshops worldwide to assist national AIDS programme staff and others in the implementation of this approach (13) (see Table 1 for an example from Indonesia).

Once HIV reaches vulnerable populations where condom use is inconsistent or needle sharing is common, epidemics are usually inevitable (14). ignoring the possibility of heterosexual HIV transmission in the wider adult population, it is possible to explore the effect of different assumptions about the peak prevalence and timing of HIV epidemics among vulnerable populations on future epidemic size. Assumed peak prevalence levels can be informed by comparison with long exposed populations from the same or neighbouring countries. Using this approach, it has been estimated that the epidemics in Eastern Europe and Asia are likely to add about 21 million infections to the HIV pandemic by 2010 if there is not a rapid and expanded response (15). Thus, even without a generalized heterosexual epidemic, the need for action is clear. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed


An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.